Yeah... the problem with the story is there's not enough details on the circumstance. FWIW I've sent a note to CW to try to contact the authors and get some of that info.

Totally get the idea that any marina would ask that a customer have coverage, and quite surprised that we don't get asked routinely (except by our home marina) to prove it - we've never, to my recollection, been asked for overnight transient spots.

Well since they were getting Drivers Licences I think they were not just visiting and were signing a contract for a season. I can't imagine signing a seasonal contract without expecting to show insurance papers.